Although Donald Trump enjoys a singularly combative relationship with the media, he is not the first US president to view the fourth estate with hostility.

Theodore Roosevelt (1901-1909) was the first president to deliberately cultivate journalists, says Mark Feldstein, journalism professor at the University of Maryland.

"The newsmen would gather around him and he would tell them stuff, some off the record, some on the record," Feldstein says.

"He made great copy — he was young, charismatic and he had young children — and all those things were new and exciting and happening at a time when newspapers were really taking off as a profit making mass media."

After the end of the Second World War, a flood of commercial television licences swept the new medium into American homes. Providing news — seen as a public benefit — became a requirement for broadcast license-holders, and presidents entered the television age.

"Presidents first began using television with President Eisenhower (1953-1961)," says Jon Marshall, from the Medill School of Journalism at Northwestern University.

"But President Kennedy (1961-1963) was the first to really master the use of television. He looked good and sounded good on television."

Richard Nixon discovered this when he famously lost the first television debate with Kennedy in 1960, appearing on camera looking sweaty and untrustworthy. By the time he became president (1969-1974), he was determined to control media coverage.

"Nixon was actually the first to set up a White House communications office that would stage events especially for television, with hand-picked audiences of people who would be favourable to what he was saying," says Marshall.

He also hired Roger Ailes — who later became the founder of Rupert Murdoch's Fox News — to coach him on how to appear on television.

But although he had enjoyed favourable press early in his career, Nixon increasingly felt that the media was against him.

Another polished media performer moved into the White House in 1993 — Bill Clinton (1993-2001) — but before the year was out, he was mired in questions about former business dealings and his sexual liaisons.

"The relationship between Clinton and the press was rocky from the very beginning," says Marshall.

"The Clintons had a penchant for secrecy, and the more they tried to hide things, the more aggressive the press became.

"Once Republicans took control of Congress, aggressive investigations by the media turned into aggressive investigations by the Republican Congress, which led to the Monica Lewinsky scandal and the impeachment hearings against President Clinton."

The secrecy that Nixon used against the press became more entrenched with each future president.

By the time George W Bush (2001-2009) was elected, increasing amounts of information were being kept secret from the media and the public.

When Barack Obama (2009-2017) took office he promised much more transparency, but his record in terms of dealing openly with the media was just as secretive as George W Bush and some of the presidents before that.

Obama's White House was very aggressive in going after reporters who published information that had been leaked from different government agencies.

President Donald Trump's (2017-) approach to the media has been open warfare. "Trump is like Nixon on steroids," says Feldstein.

"Nixon went after the press but it took months and years to develop. There has never been anything like it in terms of a president waging war from day one on the entire news media as an institution."

Political scientist Justin Buchler, from Case Western Reserve University, says accusing journalists of being shills is "one of the easiest things for politicians to do".

"That makes it very difficult for watchdog journalism to function in the current media environment," he says.

"If a news consumer hears Donald Trump say that the press are enemies of the people and the most dishonest human beings ever, and hears the press say that Donald Trump is a liar ... well, what are they to conclude?"